Many devices, such as personal digital assistants (PDAs), mobile phone-PDA hybrids, and ultra mobile personal computers (UMPCs), utilize pen-based input to help the user clearly define a selection point on a screen yet they also support touch input. The pen or stylus is usually thin, and also helps create a vertical offset between the user's hand and the screen so that targets appearing on the screen are not occluded by the users' finger or hand. However, retrieving the stylus takes time and can be inconvenient, for example, in the context of one-handed operation, or can be inefficient, for example, in the context of short/intermittent interactions.
When use of a stylus is inefficient or inconvenient, users sometimes use their finger or other “touch input” to select objects displayed on the screen of the device. For instance, this is often the case, for intermittent or short interactions such as verifying a meeting time, navigating a map, or controlling a media player.